This invention relates to a steering system for a marine propulsion unit and more particularly to an improved arrangement for actuating a control valve of a hydraulically assisted marine steering arrangement.
In many forms of marine propulsion systems, the propulsion unit is steered remotely by a steering control positioned in the operator's area of the watercraft. Normally a flexible cable is employed for transmitting the steering control from the steering wheel to the marine outboard drive. Frequently a form of hydraulic power assist is employed for assisting in the steering and this includes a linear type of hydraulic motor which is connected to the outboard drive through its tiller for assisting in the steering. A control valve of a servo system actuates the hydraulic motor in response to steering inputs at the steering wheel. The control valve is frequently operated by means of an element that is connected to a portion of the wire actuator so as to move the control valve control element in response to movement of the wire actuator element. Although these systems are effective, the wire actuator element does not move truly in a linear fashion. In addition, the interconnecting actuator between the wire actuator and the control valve element is normally restrained only where it is connected to the control valve element and the wire actuator element. As a result, the movement of the control valve may not actually track the steering needs.
For example, there may be vibrations occur in the wire actuator and these vibrations can be transmitted to the control valve element even though the vibrations do not occur in the direction of steering movement. As a result, some hunting of the position of the outboard drive may result. In addition, other difficulties can arise because of the types of constructions previously employed.
It is, therefore, a principal object of this invention to provide an improved steering control for a hydraulic steering mechanism for a marine propulsion unit.
It is a further object of this invention to provide an improved arrangement for controlling the steering control valve from a wire actuator element.
It is a still further object of this invention to provide an improved actuating arrangement for actuating a control valve of a hydraulic steering system from a wire actuator element wherein the actuating element is confined so that it can only move in the same direction as the control valve element.